Apparatus And Method For Charging Batteries

ABSTRACT

An apparatus and a method for charging a battery are disclosed. The apparatus includes a LED member that includes a single LED that is suitable for emitting light of different colours, each colour corresponding to a different operating status of the apparatus, and an acoustic signalling device that is suitable for emitting an acoustic signal indicating a malfunction of the apparatus or the battery. The method includes a first battery heating and desulphation step during which the battery is supplied with current pulses having a maximum value that is considerably lower than the maximum value of the charging current in a subsequent second constant current charging step, each current pulse being generated when the current absorbed by the battery after the delivery of a previous current pulse falls below a minimum preset value.

FIELD OF THE INVENTION

The present invention relates to an apparatus and a method for chargingbatteries, for example lead-acid batteries, that is able to carry outthe most suitable charging procedure for the battery and further enablean optimum battery charge level to be maintained, in particular when thebattery has been inactive for long periods, although it is connected toan electric plant, for example a battery of a motor vehicle that hasremained unused for relatively long periods.

BACKGROUND OF THE INVENTION

In the prior art, battery-charging apparatuses are known that are ableto recognise the type of battery to which they are connected andapplying thereto a charging procedure that is suitable for this type ofbattery.

Nevertheless, known apparatuses for charging batteries are not able torun battery charging cycles that are suitable for optimising thelifespan of the battery in any condition, in particular they are unableto recognise automatically if the battery needs a charging procedurethat enables the phenomenon of sulphation to be countered and thebattery charge to be maintained in conditions in which the battery issubject to relatively long periods of inactivity, whilst remainingconnected to the electric circuit supplied by the battery, as in thecase of batteries of motor vehicles that may remain unused forrelatively long periods.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and a method for charging abattery that enables battery-charging cycles to be run so as to maximisethe lifespan of the battery and to maintain the battery automatically inoptimum charging conditions, in particular during periods of inactivityof the battery. The apparatus and the method have to be simple and easyto use also for users who are not technically qualified.

The objects of the present invention are reached by an apparatus forcharging batteries and/or by a method for charging batteries accordingto the present invention.

Owing to the invention, it is possible to run battery-charging cycles,running the most suitable charging cycle for the battery, also solvingthe problem of possible sulphation of the battery and being able tomaintain an optimum battery charging level even during prolonged periodsof inactivity.

BRIEF DESCRIPTION OF THE DRAWINGS

One mode of carrying out the invention is disclosed below, withreference to the attached drawings, in which:

FIG. 1 is a perspective view of an apparatus according to the invention;

FIG. 2 is a perspective view from below of the apparatus of FIG. 1;

FIG. 3 is a diagram that illustrates a charging and charge maintenancecycle of a battery that is achievable with the apparatus according tothe invention;

FIG. 4 is a flow chart that illustrates the operation of the apparatusaccording to the invention;

FIG. 5 is a block diagram of an apparatus according to the invention;

FIG. 6 is a block diagram of a version of the apparatus according to theinvention;

FIG. 7 is a flow chart that illustrates the operation of the version ofthe apparatus according to the invention shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

An apparatus for charging batteries according to the invention comprisesa body 1, inside which the electric and electronic components are housed(FIG. 5 and FIG. 6) to charge a battery 2 and control the chargingprocedure.

On an upper face 3 of the body 1 a LED 4 is arranged that indicates thestatus of a battery to which the apparatus according to the invention isconnected and the status of the battery charging procedure.

The LED 4 is an RGB LED, i.e. a LED that can emit light of differentcolours such as, for example, red, yellow and green, to indicate thevarious statuses of the battery 2 and of the charging procedure, as willbe detailed below. The use of a single RGB LED enables the indication ofbattery status and of the charging procedure to be made extremely simpleand clear for the user.

In a lower face 5 of the body 1 an opening 6 is obtained through whichit is possible to access a space 7 that is suitable for housing thepower cord of the apparatus according to the invention (not shown) andthe cables for connecting the apparatus, directly or indirectly, to abattery. The opening 6 has, in a central zone thereof, a narrowing 8,the dimensions of which are chosen in such a manner as to prevent thepower cord and the connecting cables housed in the space 7 from exitingaccidentally therefrom and so as not to hinder the extraction of thepower cord and of the connecting cables from the space 7 when it isnecessary to connect the apparatus to an electric power supply 9 (FIG. 5and FIG. 6).

At least one notch 20 is made onto an edge 22 of the space 7, whichnotch 20 is provided at an open end thereof with a couple of elasticflaps 21. On the edge 22 two notches 20 are made, which are for examplearranged opposite one another, but even three or more notches 20 can bemade, which are spread along the edge 22. The notches 20 serve to fixthe power cord and/or the connecting cables in order to cooperate withthe narrowing 8 to prevent that said cables may exit from said space 7.The elastic flaps 21 serve to lock said cables after they have beeninserted into the notches 20. Fixing said cables into the notches 20also serve to prevent these cables from sliding below the edge 22 of thespace 2, so as to destabilize the apparatus according to the inventionwhen it rests with the edge 22 on a resting plane.

The apparatus according to the invention comprises a control device 10,by means of which the voltage and current are adjusted with which thebattery 2 is supplied during the charging or charge maintenanceprocedure.

The control device 10 is connected to the electric power supply 9 via asafety fuse 11.

The control device 10 is driven by a processor 14 and supplies a poweroutput 19 of the apparatus according to the invention, via an insulationtransformer 12 and a rectifier 13. The power output 19 is intended to beconnected, directly or indirectly, to a battery 2 to supply the battery2 during the charging or charge maintenance procedure.

The processor 14 is supplied by the insulation transformer 12 and isconnected to the control device 10 by an optoinsulator 15 that serves toprotect the processor 14 from possible overvoltage coming from theelectric power supply 9 through the control device 10.

The processor 14 is further connected, directly or indirectly, to abattery 2, so as to be able to read the voltage of the battery 2 duringthe charging or charge maintenance procedure.

The apparatus according to the invention is further provided with acurrent sensor 16, which is operationally connected to the processor 14and to the rectifier 13, of a thermal sensor 18 which is operationallyconnected to the processor 14 and with a relay 17 interposed between therectifier 13 and the power output of the apparatus. The current sensordetects the value of the charging current sent to the battery 2 andcommunicates it to the processor 14. The thermal sensor is used todetect any overheating of the apparatus and to notify such overheatingto the processor 14. Lastly, the relay 17 is used to interrupt or enablethe supply of current to the battery 2.

Besides the RGB LED 4, the processor 14 is also operationally connectedto an acoustic signalling device 23 intended for emitting an acousticsignal for signalling abnormal conditions of the apparatus according tothe invention or the battery 2.

The procedure of charging a battery 2 with the apparatus according tothe invention comprises the following steps:

-   -   a preliminary step of checking the battery 2 connected to the        apparatus according to the invention, to check if it is a type        of battery 2 that is suitable for being charged by the apparatus        according to the invention and the battery 2 is not damaged.        After connecting the apparatus according to the invention to an        electrical supply grid, the processor 14 checks that the        apparatus is working. If the check is positive, the processor 14        commands the LED 4 so that it emits a flashing red light, which        indicates to the user that the apparatus is ready to be used. If        the check is negative, for example if the safety fuse 11 is        broken, the processor 14 controls the LED 4 so that it emits a        luminous alarm signal, for example a fixed red light, and        activates the acoustic signalling device 23 that emits an        acoustic alarm signal, which indicates to the user, together        with the luminous alarm signal, that the apparatus is not        useable. The use of an acoustic alarm signal combined with a        luminous alarm signal has the advantage to ensure that the user        is warned of a malfunction of the apparatus according to the        invention, or, as detailed below, of the battery 2, even if the        luminous signalling device, for any reasons, is inactive or is        not visible or is hardly visible.

The type of battery 2 connected to the apparatus according to theinvention is checked by measuring the voltage to the terminals, to checkif it is compatible with the voltage of the type of battery 2 for whichthe apparatus according to the invention is intended, for example, inthe case of lead-acid batteries, a voltage to the terminals that is notgreater than about 14.5 V. Further, if the voltage measured at theterminals of the battery 2 is less than about 8.5 V, it is consideredthat the battery 2 is irremediably damaged. In both cases, i.e. voltageto the terminals above 14.5 V, or lower than 8.5 V, the processor 14does not start up the charging procedure and the aforementioned luminousalarm signal and acoustic alarm signal are activated that warn the userthat the user cannot proceed to charge the battery 2 because the battery2 is not of a type that is suitable for being charged with the apparatusaccording to the invention, or is damaged.

A first, so-called “soft start” step, in which the apparatus accordingto the invention emits square wave-shaped current pulses, with intensityof about 2 A, i.e. below the normal maximum charging current of thebattery 2, which, for example in the case of lead-acid batteries, isabout 3.6 A. The duration of the current pulses is not predetermined butdepends on the status of the battery 2. In fact, the descent front ofthe current pulses is less steep the greater the battery 2 charge is.When the value of the current absorbed by the battery 2 falls belowabout 100 mA a new current pulse is generated. Thus also the frequencyof the pulses depends on the charge status of the battery 2, decreasingas the battery 2 charge increases.

This first “soft start” step lasts about 30 minutes, at the end ofwhich, if the battery has not reached a voltage at the terminals ofabout 10.5 V, the processor 14 interrupts the charging procedure,deeming the battery to be damaged and activates the aforementioned alarmsignals.

This first step is used to place the battery 2 in the optimum conditionfor charging and eliminating possible sulphation of the battery 2,breaking possible lead sulphate crystals that have been formed over timeon the terminals of the single cells of the battery and that hinderbattery recharging, preventing over time the complete rechargingthereof.

A second step, which starts at the end of the first “soft start” step,i.e. after 30 minutes from the start of the charging procedure, in whichthe apparatus according to the invention supplies the battery 2 with aconstant intensity current that, in the case of lead-acid batteries, isabout 3.6 A. During this step the voltage at the terminals of thebattery increases progressively until it reaches a maximum voltage valueat which the constant current charging step stops. For lead-acidbatteries, taking into account the fact that the maximum voltage at theends of each cell can vary between approximately 2.37 V and 2.4 V, themaximum voltage reached at which constant current charging step stopscan be set at about 14.2 V, for batteries with six elements.

A third step, the start of which is controlled by the processor 14 whenthe voltage at the terminals of the battery 2 has reached the aforesaidpreset maximum value.

In this third step, the apparatus according to the invention suppliesthe battery 2 with constant voltage equal to the aforesaid presetmaximum value. During this step, the charging current of the batterydecreases progressively until a preset minimum value is reached, atwhich the processor 14 ends charging of the battery. This preset minimumvalue depends on the capacity of the battery. For example, in the eventof a battery with a capacity of 20 Ah, the aforesaid minimum value canbe fixed at approximately 200 mA.

When the three aforesaid steps of charging the battery 2 are being run,the LED 4 emits a fixed yellow light that shows the user that theapparatus according to the invention is running the charging procedureof the battery.

At the end of the charging procedure, the apparatus according to theinvention can be left connected to the battery 2 to run a chargemaintenance procedure, the object of which is to maintain the battery 2charged at an optimum level over time, either when the battery 2 is inuse and when the battery 2 is not in use, i.e. during periods ofinactivity of the battery 2. Maintaining an optimum charging level ofthe battery 2 enables the performance of the battery 2 to be optimisedand the lifespan of the battery 2 to be maximised.

The charge maintenance procedure comprises continuous monitoring of thevoltage at the terminals of the battery 2 by means of the processor 14.When the processor 14 detects that the voltage at the terminals hasreached a preset minimum value, the start of a short constant voltagecharging cycle is commanded that ends when the voltage at the terminalsreaches a preset maximum value.

Said maximum and minimum values can be calculated with reference to anaverage maintenance voltage value that, in the case of lead-acidbatteries, can be fixed, for example, at a value of 13.6 V. Said maximumand minimum values can, for example, correspond to a deviation of ±0.5 Vfrom said average value, i.e. respectively to 14.1 V and 13.1 V.

Running of the maintenance step is indicated by the LED 4 by theemission of a fixed green light.

The various operating steps of the apparatus according to the inventionare illustrated in the diagram of FIG. 3 showing the trend of thecurrent supplied by the apparatus in the different steps and in the flowcharts of FIGS. 4 and 7 that illustrate the operating logic of theapparatus according to the invention.

The apparatus according to the invention is provided with a protectionsystem against possible overtemperature that could damage the componentsof the apparatus, reducing the efficiency of the components or damagingthe components irreparably.

The protection system is managed by the processor 14 via the thermalsensor 18, which measures the temperature inside the apparatus accordingto the invention.

If the processor 14 detects that the temperature measured by the thermalsensor 18 exceeds a first preset threshold value, for example 60° C., areduction is commanded of the maximum value of the current supplied bythe apparatus according to the invention. This reduction can be, forexample, equal to 25% of said maximum value. The object of thisreduction is to enable the temperature of the apparatus to be decreased.

If, despite the decrease of the maximum supplied current the temperaturecontinues to increase, reaching a second preset threshold value, forexample 70° C., the processor 14 commands a further decrease of maximumvalue of the current supplied, for example equal to 50%, to avoid afurther temperature increase.

If the temperature of the apparatus according to the invention continuesto increase, the processor 14 switches off the apparatus and activatethe alarm signals.

If, on the other hand, the temperature decreases, the processor 14returns the value of the supplied current to 75% of the maximum valuewhen the temperature falls below the second threshold value and to 100%of maximum value when the temperature falls below the first thresholdvalue.

The threshold values are chosen according to the features of thecomponents of the apparatus, i.e. on the basis of the maximum operatingtemperature that they can bear without being damaged or diminishingperformance thereof.

The aforesaid protection system enables the apparatus according to theinvention to be run always in the best conditions, regardless of theenvironmental conditions in which the apparatus is arranged to operateand the apparatus to be protected from possible damage caused byoverheating.

In the present description, reference has been made to charging alead-acid battery; nevertheless, it is clear that the apparatus andmethod disclosed are applicable also to charging other types ofbatteries.

In the practical embodiment, the materials, dimensions andconstructional details may be different from those indicated but betechnically equivalent thereto without thereby falling outside the scopeof the present invention.

1-12. (canceled)
 13. Apparatus for charging batteries comprising a bodyinside which an electric and electronic component is housed forsupplying a charging current to a battery, a supply cable for connectingthe apparatus to an electrical supply grid, connecting cables forconnecting the apparatus, directly or indirectly, to a battery, whereinsaid apparatus comprises a LED member that is suitable for indicating anoperating status of the apparatus, said LED member comprising a singleLED that is suitable for emitting light of different colours, eachcolour corresponding to a different operating status of the apparatus,and an acoustic signalling device that is suitable for emitting anacoustic signal indicating a malfunction of the apparatus or thebattery.
 14. Apparatus according to claim 13, further comprising a spaceintended for housing said supply cable and said connecting cables. 15.Apparatus according to claim 14, wherein said space communicates withthe exterior by an opening provided, in a central zone thereof, of anarrowing having dimensions such as to prevent an accidental escape fromsaid space of said supply cable and of said connecting cables. 16.Apparatus according to claim 14, wherein at least one notch is made onan edge of the space, said notch being provided with a couple of elasticflaps arranged at an open end of said notch.
 17. Apparatus according toclaim 16, wherein at least two notches are made on said edge. 18.Apparatus according to claim 13, wherein said LED member is arranged onan upper face of the apparatus.
 19. Apparatus according to claim 18,wherein said opening is made on a lower face of the apparatus, oppositesaid upper face.
 20. Method for charging a battery by means of anapparatus for charging batteries comprising a first battery heating anddesulphation step, a second constant current charging step and a thirdconstant voltage charging step, wherein in said first step the batteryis supplied with current pulses having a maximum value that is lowerthan the maximum value of the charging current in said second constantcurrent charging step, each current pulse being generated when thecurrent absorbed by the battery after the delivery of a previous currentpulse falls below a minimum preset value.
 21. Method according to claim20, wherein said current pulses are pulses having a square wave shape.22. Method according to claim 20, further comprising a fourth step ofmaintaining the charge of the battery, said fourth step comprisingstarting a constant voltage charging step if the voltage at theterminals of the battery reaches a preset minimum value and interruptingsaid constant voltage charging step when the voltage at the terminals ofthe battery reaches a preset maximum value.
 23. Method according toclaim 20, further comprising monitoring the operating temperature ofsaid apparatus and varying the maximum value of the current dispensed bythe apparatus, said varying comprising reducing to a first preset valuethe maximum value of the current dispensed by the apparatus when theoperating temperature thereof reaches a first threshold value, furtherreducing to a second preset value the maximum value of the currentdispensed by the apparatus when the operating temperature thereofreaches a second threshold value and switching off the apparatus if theoperating temperature thereof exceeds said second threshold value. 24.Method according to claim 23, comprising returning the value of thedispensed current to said first preset value if the temperature of theapparatus falls below said second threshold value and returning thevalue of the dispensed current to said maximum value if the temperatureof the apparatus falls below said first threshold temperature.